Prior art electrostatic precipitators, wherein there are concentric spaced apart generally circular in cross section cylindrical electrode structures have been provided with supporting base elements for carrying the electrodes of such electrostatic precipitators, and in the construction of supporting bases for such collector electrodes, it has been a problem to properly assemble drain troughs as well as collector troughs and also inlet venturi structures all within a reasonable plane and so as to provide for uniformity of structure as well as compactness and efficient aerodynamic operation thereof.